Why can I add characters to strings but not characters to characters?

Question

So I wanted to add a character to a string, and in some cases wanted to double that characters then add it to a string (i.e. add to it itself first). I tried this as shown b

Answer 1

When you do char s = 'X'; String string = X + X;

Why not do this instead? char s = 'X'; String string = s + s;